1. Field of the Invention
The present invention relates to a method of preparing a compound semiconductor having a carrier-injection layer or an electrode-drawing layer, which is formed by a crystal regrowth method and a selective crystal growth method.
2. Description of the Related Art
For the purpose of improving the performance of a compound semiconductor device, the structure suitable for the shortening tendency of a channel has been investigated in an electron device, and also the side-joint structure fitted for the OEIC (Optoelectronic Integrated Circuit) has been investigated in a semiconductor laser. As an effective method to realize these structures, a self-alignment method of forming a carrier-injection layer or an electrode-drawing layer, by a crystal regrowth and a selective crystal growth methods, has been generally used.
In this case, the surface of a substrate or an epitaxial growth layer is subjected to an impurity pollution or a physical damage, during the processes of exposure in the air, etching, washing and the like. Then, in case where a crystal regrowth is directly effected on these surfaces as they are, the performance or the life time of a device will be exceedingly deteriorated. For that reason, the cleaning of the surface and the removal of the damaged layer have been executed in a crystal growth chamber by a vapor phase etching method, successively followed by effecting the crystal regrowth procedure. The compound semiconductor device prepared by such method, however, poses a problem that the carrier will be stored on the regrowth surface as shown in FIG. 1, though the purity of the surface will be improved.